• C++中的补码公式与位域


    C++中的补码公式与位域:

    代码很简单就不多说:

    补码公式:

    #include <iostream>
    using namespace std;
    
    void operator_1(void);
    void operator_2(void);
    void operator_3(void);
    int main(void) {
    
            /*
            -x = ~x+1 = ~(x-1)
            ~x = -x-1
            -(~x) = x+1
            ~(-x) = x-1
    
    
            x+y = x - ~y-1 = (x|y) + (x&y)
            x-y = x + ~y+1 = (x|~y) - (~x&y)
            x^y = (x|y) - (x&y)
            x|y = (x& ~y) + y
            x&y = (~x|y) - ~x
    
    
            x==y :  ~(x-y|y-x)
            x!=y :  x-y|y-x
            x<y  :  (x-y) ^ ((x^y) & ((x-y) ^x))
            x<=y :  (x|~y) & ((x^y) | ~(y-x))
            x<y  :  (~x&y) | ((~x|y) & (x-y))   //unsigned
            x<=y :  (~x|y) & ((x^y) | ~(y-x))   //unsigned
    
            */
            operator_1();
            operator_2();
            operator_3();
            return 0;
    }
    void operator_1(void) {
            int x = 1;
            cout << "-x = " << -x << "   ~x+1 = " << ~x + 1 << endl;
            cout << "~x = " << ~x << "   -x-1 = " << -x - 1 << endl;
            cout << "-(~x) = "<< -(~x) << "   x+1 = " << x + 1 << endl;
            cout << "-(~x) = "<< -(~x) << "   x-1 = " << -x -1 << endl;
    }
    void operator_2(void) {
            int x = 3, y = 5;
            cout << endl;
            cout << "x: " << x << "y: " << y << endl;
            cout << "x+y=" << x+y << "   x- ~y-1= " << x - ~y - 1
            << "  (x|y)+(x&y) = " << (x|y) + (x&y) << endl;
            cout << "x-y=" << x-y << "   x+ ~y+1= " << x + ~y + 1
            << "  (x|~y) - (~x&y) = " << (x|~y) - (~x|y) << endl;
    
            cout << "x^y=" << (x^y) << " (x|y) - (x&y)" << (x|y) - (x&y) << endl;
            cout << "x|y=" << (x|y) << " (x& ~y) + y = " << (x& ~y) + y << endl;
            cout << "x&y=" << (x&y) << " (~x|y) - ~x = " << (~x|y) - ~x << endl;
    }
    void operator_3(void) {
            int x = -3, y = -5;
            unsigned int x_t = -1, y_t = -5;
            cout << "x: " << x << "y: " << y << endl;
            cout << "x==y =" << (x==y) << "  ~(x-y|y-x) =" << ~(x-y|y-x) << endl;
            cout << "x!=y =" << (x!=y) << "  x-y|y-x =" << (x-y|y-x) << endl;
            cout << "x<y =" << (x<y) << "  (x-y) ^ ((x^y) & ((x-y)^x))=" << ((x-y) ^ ((x^y) & ((x-y)^x))) << endl;
            cout << "x<=y =" << (x<=y) << "  (x|~y) & ((x^y) |~ (y-x))=" << ((x|~y) & ((x^y) |~ (y-x))) << endl;
            cout << "unsigned: x<y =" << (x_t<y_t)
            << "  (~x&y) | ((~x|y) & (x-y))" << ((~x_t&y_t) | ((~x_t|y_t) & (x_t-y_t))) << endl;
    
            cout << "unsigned: x<=y =" << (x_t<=y_t)
            << " (~x|y) & ((x^y) | ~(y-x) =" << ((~x_t|y_t) & ((x_t^y_t) |~ (y_t-x_t))) << endl;
    
    }
    

    位域

    #include <stdio.h>
    typedef struct bs {
            int a:2;
            int b:1;
            int c:12;
            unsigned d:4
    
    }bs;
    struct bit_2 {
            unsigned a:2;
            unsigned :2;  //It can't use
            unsigned :0;  //NULL
    
            unsigned b:4;
            unsigned c:4;
    
    };
    int main(void) {
            bs bit;
            printf("sizeof(%d) 
    ",sizeof(struct bs));
            bit.a = 4;
            bit.b = 1;
            bit.c = 34235;
            printf("a: %d   b: %d  c: %d
    ", bit.a, bit.b, bit.c);
    
            return 0;
    }
    
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  • 原文地址:https://www.cnblogs.com/lyxf/p/12231472.html
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